JP7009502B2 - Drive belt used in continuously variable transmissions with cross section members and ring stacks - Google Patents

Description

The present disclosure relates to a drive belt used in a continuously variable transmission having two pulleys and a drive belt. Such drive belts are known in International Publication No. 2015/063132, which is an international patent application, and are mounted on several continuous bands, each of which is superposed on each other, a stack of flat, thin rings. Includes rows of crossing members. The transverse member is capable of moving along the circumference of the ring stack while forming an opening that accommodates and limits each perimeter of the ring stack. This special type of drive belt is also referred to as a push type drive belt or push belt.

In the description below, the axial direction, the radial direction, and the circumferential direction are defined with respect to the drive belt when arranged in a circular posture. Further, the thickness dimension of the crossing member is defined in the circumferential direction of the drive belt, the height dimension of the crossing member is defined in the radial direction, and the width direction of the crossing member is defined in the axial direction. Has been done.

Each of the known transverse members consists of a base portion, a central portion and an upper portion. The central portion of the transverse member extends radially while interconnecting the base portion and the upper portion of the transverse member. On both sides of the central portion, the transverse member forms an opening between the base portion and the upper portion of the transverse member to accommodate the respective ring stack of the drive belt. At each opening, the radially outwardly facing lower surface of the transverse member contacts and supports the ring stack on the radial outer side. These lower surfaces of the opening with respect to the base portion of the transverse member are hereinafter referred to as support surfaces.

In a row of crossing members of a drive belt, at least a portion of the front body surface of the crossing member abuts on at least a portion of the rear body surface of each preceding crossing member in the row, whereas the rear of the crossing member. At least a portion of the side body surface abuts on at least a portion of the front body surface of the subsequent crossing member, respectively. At least one of these anterior and posterior body surfaces of the transverse member, eg, the anterior body surface, comprises a convexly curved surface portion that extends axially. This curved surface portion divides the front body surface into a radial outer surface portion and a radial inner surface portion oriented at a predetermined angle with respect to each other. The crossing members abutting in the drive belt are capable of tilting with respect to each other, while maintaining contact with each other at and through such curved surface portions, and therefore such. The curved surface portion is hereinafter referred to as a tilting edge portion. Tilted edges allow a row of cross members of the drive belt to follow the local curvature of the ring stack brought about by the transmission pulley.

The crossing member is further provided with a protrusion protruding from the front body surface of the crossing member and a corresponding hole provided in the rear body surface. In the row of crossing members of the drive belt, the protrusions of the subsequent crossing member are at least partially located in the holes of the preceding crossing member, thereby being perpendicular to the circumferential direction of the drive belt. Mutual displacement of abutting transverse members in a plane is blocked, or at least limited. Normally, the protrusions and holes have the same shape as a whole, for example having a substantially cylindrical shape or a slightly conical shape.

As mentioned above, in the drive belt, the cross member is movable with respect to the ring stack along the circumference of the ring stack. This has the advantage that during the operation of the drive belt, the ring stack is tensioned at a relatively low level of torque transmitted by the drive belt between the pulleys, at least compared to other types of drive belts. Have. However, on the other hand, it is known that such sliding motion or slip between the transverse member and the ring stack causes a small but assumed friction loss. It is known that such sliding motion can be preferably minimized by arranging the tilted edges of the transverse member as close as possible to the radial inside of the ring stack in the height direction. Theoretically, at this point, the tilted edges are preferably arranged so as to coincide with the support surface of the cross member of interest.

However, according to the present disclosure, placing the tilted edge near the support surface presents problems or drawbacks that can be understood as follows. The closer the tilting edges are to the support planes, the sharper the transition edges between them must be. Also, the sharper the transition edge, the higher the contact stress in the ring stack as a result. In fact, the yield stress of the innermost radial ring in the ring package can be exceeded during the operation of the drive belt due to the high contact stress, even impairing the useful life of the innermost ring.

According to the present disclosure, beyond expectations, such drawbacks are somewhat lower than the protrusions, especially by including a vertical offset between the protrusions and the holes of the individual transverse members. That is, it can be reduced by arranging the drive belt more inward in the radial direction. By this means, the cross member is of the drive belt because the protrusion is forcibly inserted into the (lower) hole, even when traveling linearly between the pulleys. Tilt forward in a row. This, in particular, the contact between the radial inside of the ring stack and the transition edge between the support surface and the tilting edge is suitably avoided, or at least its strength is reduced. There is.

In a later view, in conventional drive belts, the transition edge is smoothly rounded with a relatively large radius of curvature (this is achieved by the relatively large spacing between the support surface and the tilted edge). Therefore, it can be acknowledged that the above-mentioned means do not bring about such an effect. For example, in a conventional drive belt, the tilting edge portion is separated from the support surface by about 1 mm, so that the radius of curvature of the transition edge portion can be 0.5 mm or more.

式中、Ｏ＿ｍｉｎは、前記オフセットＯの最小値を表し、Ｒｒ＿ｍｉｎは、特にトランスミッションプーリにおける、駆動ベルトの長手方向の最小の曲率半径を表し、Ｄは、横断部材の厚さを表す。 In particular, the radial inward offset O of the holes with respect to the protrusions of the individual transverse members according to the present disclosure can be geometrically quantified as follows:

In the equation, O_min represents the minimum value of the offset O, Rr_min represents the minimum radius of curvature in the longitudinal direction of the drive belt, especially in the transmission pulley, and D represents the thickness of the transverse member.

Due to the minimum offset O_min according to equation (1), the transverse member in the drive belt is located radially inside the virtual circle whose transition edge has a radius Rr_min and is located at the edge between the support surface and the rear body surface. It tilts forward on the drive belt within the crossing range.

For example, for a typical drive belt with an Rr_min value of 30 mm and a D value of 1.6 mm, a minimum offset of 11 micrometers, O_min, is calculated by equation (1). The actual design values for the offset O, which tolerate some manufacturing variability and other uncertainties, are 1.5 to 5 times O_min, or 15 to 75 microns. Preferably, according to the present disclosure, such an actually applied offset O, and thus the forward tilt of the transverse member resulting from it, is 5 times such a minimum required value O_min, more than anything else. It is preferably limited to 3 times. Otherwise, the adjustment force between the protrusions will be unnecessarily high and / or the ring stack will instead be forced into contact with the trailing edge of the support surface.

Hereinafter, the above-mentioned novel drive belt will be described with reference to the drawings. In the drawings, the same reference numerals indicate the same or equivalent parts.

A schematic perspective view of a continuously variable transmission having a drive belt running over two pulleys is shown. A schematic cross-sectional view of a known drive belt oriented in the circumferential direction of the drive belt is shown. A schematic view of a known crossing member of a drive belt in the width direction is shown. FIG. 3 shows an enlarged view of a part of the known crossing member drawn. An enlarged view of a part of a new crossing member is shown. FIG. 3 shows a schematic view of a straight track portion of a drive belt with a new cross section.

FIG. 1 schematically shows, for example, a continuously variable transmission for use in an automobile between an automobile prime mover and a drive wheel. Continuously variable transmissions are generally shown using reference numeral 1. The continuously variable transmission 1 has two pulleys 2 and 3 and a drive belt 6 provided in a closed loop around the pulleys 2 and 3. Each of the pulleys 2 and 3 is provided with a pulley shaft 4 and two pulley sheaves 7 and 8, and the first pulley sheave 7 thereof is fixed to the pulley shaft 4 of each of the pulleys 2 and 3. The second pulley sheave 8 is axially displaceable with respect to such a pulley shaft 4 while being fixed to the pulley shaft 4 in the rotational direction. During the operation of the transmission 1, the drive belt 6 is tightened in each of the pulleys 2 and 3 by the pulley sheaves 7 and 8 of the pulleys 2 and 3 with a traveling radius Rr placed between them. Can be changed to change the speed ratio of the transmission by moving the pulley sheaves 7 and 8 of the pulleys 2 and 3 in directions away from each other.

The drive belt 6 has two sets of continuous bands or rings that are radially superposed on each other, hereinafter referred to as the ring stack 9. The cross member 10 of the drive belt 6 is arranged on the ring stack 9 and forms a substantially continuous row along the entire circumference of the drive belt 6. For simplicity, only some of these crossing members 10 are shown in FIG.

The crossing member 10 is movably provided with respect to the ring stack 9 at least along the circumference of the ring stack 9. As a result, the transverse members 10 are pressed against each other and are pressed forward against each other along the circumference of the ring stack 9 in the rotational direction of the pulleys 2 and 3, thereby using friction between the transmission pulleys 2 and 3. The torque can be transmitted with. The ring stack 9 (ring) of the cross member 10 and the drive belt 6 is usually made of steel. This particular type of transmission 1 and its operating principles are widely known in their own right.

FIG. 2 shows the drive belt 6 oriented in the length direction or the circumferential direction C, that is, directed in the width direction or the axial direction A of the drive belt 6 and perpendicular to the height direction or the radial direction R. In the cross section shown, one exemplary form of the drive belt 6 is shown. In FIG. 3, only the crossing member 10 of FIG. 2 is shown in a side view as viewed in the axial direction A.

In FIG. 2, the ring stack 9 is shown in cross-sectional view and one cross-sectional member 10 of the drive belt 6 is shown in front view. In this case, each ring stack 9 consists of five individual flat, thin and flexible endless rings 5, the endless rings 5 being concentrically superposed on each other in the radial direction R, where each ring stack 9 is It is formed. However, in practice, these ring stacks 9 often include six or more endless rings 5, such as nine or twelve endless rings 5, and many more are possible.

In FIGS. 2 and 3, the transverse member 10 has a substantially trapezoidal base portion 13, a relatively narrow central portion 14, and a substantially triangular upper portion 15, in order of radius R. An opening 33 is formed between the base portion 13 and the upper portion 15 on both sides of the central portion 14, and the ring stack 9 is housed in the opening 33. At each opening 33, the support surface 42 of the base portion 13 facing outward in the radial direction comes into contact with the radial inside of each ring stack 9 during operation.

The front surface of the transverse member 10 is generally indicated by reference numeral 11 while the rear surface of the transverse member 10 is generally indicated by reference numeral 12. Hereinafter, the front surface 11 and the rear surface 12 are generally referred to as main body surfaces 11 and 12. In the drive belt 6, at least a part of the front surface 11 of the cross member 10 abuts on at least a part of the rear surface 12 of the subsequent cross member 10, whereas at least a part of the rear surface 12 of the cross member 10 precedes. Contact with at least a part of the front surface 11 of the crossing member 10.

The crossing member 10 receives a tightening force exerted between the discs 7 and 8 of the pulleys 2 and 3 via the contact surface 37 of the crossing member 10. One such contact surface 37 is provided on each axial side of the transverse member 10. These contact surfaces 37 extend outward to each other in the radial direction, whereby an acute angle is formed between the contact surfaces, and this acute angle is referred to as a belt angle Φ, and pulleys 2 and 3 are formed. It almost coincides with the pulley angle Θ formed between the pulley sheaves 7 and 8 of.

The crossing member 10 is provided with a protruding portion 40 protruding from the front surface 11 of the crossing member 10 and a corresponding hole 41 provided in the rear surface 12 of the crossing member 10. In the drive belt 6, the protrusion 40 of the subsequent crossing member 10 is at least partially disposed in the hole 41 of the preceding crossing member 10, thereby being perpendicular to the circumferential direction C of the drive belt 6. Mutual displacement of these adjacent transverse members 10 in the plane is blocked, or at least limited. Usually, a reference gap of 10 to 50 microns, that is, a protrusion / hole-gap is provided between the outer circumference of the protrusion 40 and the inner circumference of the hole 41.

A swinging edge portion 18 is formed on the front surface 11 of the base portion 13 of the crossing member 10. The swinging edge 18 is formed by a convexly curved region of the front surface 11, which is formed into two portions of the front surface 11 oriented in the radial direction R at a predetermined angle with respect to each other. Divide. An important function of the swinging edge 18 is that in pulleys 2 and 3, when adjacent crossing members 10 are in a slightly rotated or tilted position with respect to each other, between adjacent crossing members 10. It is to provide mutual push contact. In order to achieve the minimum contact stress in the push contact in a preferred manner, and for the stability of such contact, the swinging edge 18 is preferably along the entire local width of the transverse member 10. Is postponed. The swinging edge portion 18 is preferably arranged near the support surface 42, that is, inside the support surface 42 in the radial direction with a minimum distance Drc. However, as the distance Drc becomes smaller, the transition edge portion 50 between the front surface 11 of the crossing member 10 and the support surface 42 becomes sharper. This latter form in the design of the transverse member 10 is shown in FIG. 4 with an enlarged view of the region E shown by the dotted circle in FIG. On the left side of FIG. 4, the distance Drc from the relatively large swinging edge to the support surface is shown, and at least on the right side of FIG. 4, having a relatively small swing edge to the support surface. Compared to the design of the transverse member 10, a relatively large radius of curvature Rte is allowed to be provided at the transition edge 50. In practice, as shown in FIG. 4, the radius of curvature Rte is from the swinging edge to the support surface to ensure that the swinging edge 18 does not overlap the transition edge 50 in mass production. Is somewhat smaller than the distance Drc.

In FIG. 4, the transition edge portion 50 is drawn as an arc having a radius Rte. However, in practice, the transition edge 50 does not have to be uniformly shaped, in which case the contour of the transition edge 50 is (the closest fit) of an arc of radius Rte, at least in the context of the present disclosure. ). Therefore, the radius Rte of the transition edge between the support surface 42 and the front surface 11 may seem insignificant. However, the transition edge 50 actually contacts the radial inside of each ring stack 9 to increase the overall stress level of the ring stack 9. Moreover, especially in this latter point, it was found that when the radius Rte of the transition edge portion 50 is less than 0.5 mm, particularly less than 0.3 mm, a substantial stress increasing effect is produced.

According to the present disclosure, an offset O is provided between the radial position of the protrusion 40 of the transverse member 10 and the radial position of the hole 41 such that between the transition edge 50 and the ring stack 9. Contact can be suitably avoided, or at least the strength can be reduced. Therefore, by lowering the overall stress level of the ring stack 9, the load capacity and / or life of the drive belt 6 can be increased.

This novel design of the cross member 10 is schematically shown in FIG. 5 with an enlarged view of a portion of the cross member 10 corresponding to the region F shown by the dotted ellipse with respect to the cross member 10. There is. In FIG. 5, the central axis of the cylindrical protrusion 40 is indicated by the solid line CA40, and the central axis of the hole 41 is indicated by the broken line CA41. Therefore, the offset O corresponds to the distance between the central axis CA40 of the cylindrical protrusion 40 and the central axis CA41 of the hole 41. According to the present disclosure, such an offset O is about 15 micrometers to 75 micrometers in the normal thickness of the cross member 10 of 1.4 mm to 1.8 mm. Therefore, even at the scale of FIG. 5, the offset O is exaggerated.

When the offset O included in the new crossing member 10 exceeds the reference protrusion / hole-gap and the crossing member 10 is pressed against each other in the row of drive belts 6, the crossing member 10 is placed in an adjacent crossing member 10. By forcibly inserting the protrusion 40 of the first crossing member 10 into the hole 41 (at a lower position) of the ring stack 9, it is tilted forward with respect to the ring stack 9. This causes the contact between the radial inside of each ring stack 9 and the transition edge 50 of the transverse member 10 to extend between the transmission pulleys 2 and 3, as schematically shown in FIG. It can be preferably avoided in the linear portion of the existing drive belt 6. Furthermore, the crossing member 10 enters between the two pulley sheaves 7 and 8 at such an inclined position with respect to the ring stack 9, whereby the crossing members sandwiched between the pulley sheaves 7 and 8 respectively. The radial position of the transition edge 50 of the member 10 is somewhat lower than the radial position of the opposite edge of the support surface 42 on the side of the rear surface 12 of the transverse member 10. As a result, the strength of the contact between the inside of each ring stack 9 in the radial direction and the transition edge portion 50 between the support surface and the tilting edge portion is reduced at least preferably.

The present disclosure relates to and includes all features of the appended claims, in addition to the whole of the above description and all the details of the accompanying drawings. The parenthesized reference numerals in the claims do not limit the scope of the claims, but are provided merely as non-binding examples of the respective features. The features described in the claims can optionally be applied separately in any product or in any way, but any combination of any two or more of these features can also be applied.

The inventions represented by the present disclosure are not limited to embodiments and / or examples expressly referred to herein, but also include amendments, modifications and practical applications thereof, especially to those of skill in the art. it is obvious.

Claims (7)

A crossing member (10) used for a drive belt (6) having a ring stack (9) and a plurality of continuous crossing members (10).
The crossing member (10) is movably arranged in the ring stack (9), and each of the crossing members (10) is provided with an opening (33) for accommodating the ring stack (9). The opening (33) is defined by a support surface (42) provided below the opening (33) and above the base portion (13) of the cross member (10). Each of the crossing members (10) has a swinging edge portion (18) as a convexly curved region of the front surface (11) of the crossing member (10), the support surface (42), and the crossing member. A transition edge portion (50) similarly curved in a convex shape is provided between the front surface (11) of the (10), and each of the crossing members (10) has the crossing member (10). ) On the front surface (11) of the crossing member (40) and the crossing member (10) arranged on the opposite side of the crossing member (10) from the front surface (11) of the crossing member (10). ) Is further provided with a hole (41) on the rear surface (12), and the protrusion (40) and the hole (41) are formed into a substantially conical shape or at least a cylindrical shape. In 10),
An offset (O) is provided between the central axis (CA40) of the protrusion (40) and the central axis (CA41) of the hole (41), and the offset (O) provides the hole (41). Is located on the rear surface (12) lower than the protrusion (40) on the front surface (11), that is, below the cross member (10) .
The cross member (10), wherein the offset (O) is from 15 micrometers to 75 micrometers . The crossing member (10) according to claim 1, wherein the curved radius of curvature (Rte) of the transition edge portion (50) is smaller than 0.5 mm, particularly smaller than 0.3 mm. The rocking edge (18) is located less than 0.9 mm below the support surface (42), particularly less than 0.7 mm below the support surface (42), and particularly the support surface (42). The crossing member (10) according to claim 1 or 2, characterized in that it is located less than 0.6 mm below. Claim 1 is characterized in that a gap is formed between the outer periphery of the protrusion (40) and the inner circumference of the hole (41), and the gap is 10 micrometers to 50 micrometers. The crossing member (10) according to any one of items 1 to 3 . Any of claims 1 to 4 , wherein the offset (O) is greater than half the difference between the diameter of the outer circumference of the protrusion (40) and the diameter of the inner circumference of the hole (41). The crossing member (10) according to item 1. The offset (O) applied to the cross member (10) is of the formula:

Therefore, it is larger than the minimum value (O_min) for the offset.
In the equation, Rr_min represents the minimum radius of curvature in the longitudinal direction of the drive belt (6), and D is measured between the front surface (11) and the rear surface (12) of the cross member (10). A drive belt (6) provided with a plurality of crossing members (10) according to any one of claims 1 to 5 , characterized in that it represents the maximum thickness of the crossing member (10). Claimed that the offset (O) applied to the cross member (10) is less than 5 times, preferably less than 3 times, the minimum value (O_min) for the offset. Item 6. The drive belt (6) according to Item 6.

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